Lupus is an autoimmune disease that causes symptoms such as fatigue, fever, rashes and joint pain. It can lead to serious organ damage, and occurs more often in women than in men.

For the new study, University of Michigan researchers analyzed data from about 2.4 million people in the southeastern part of the state and found that lupus affected one in 537 black women, compared with one in 1,153 white women.

Black women were more likely to be diagnosed with lupus at a younger age and during childbearing years, the researchers found.

Along with developing lupus earlier in life, black women with the disease also had higher rates of serious health complications, such as kidney failure and neurological problems, according to the study, which was released online in advance of print publication in the journal Arthritis & Rheumatism.

"There is a very poor understanding of what causes lupus," study lead author Emily Somers, an assistant professor in the departments of internal medicine and obstetrics and gynecology, said in a university news release. "Identifying the population and dynamics involved helps us target our resources more effectively and better recognize risk factors for the development and progression of the disease."

"We found a striking health disparity between black and white women," Somers said. "The disproportionate burden of disease was compounded by the fact that for black females, peak risk of developing lupus occurred in young adulthood while the risk of disease among white women was spread out more evenly through mid-adulthood and tended to be less severe."

"[Lupus that begins] before or during reproductive years can have significant implications for childbearing and risks in pregnancy, and of course may lead to a higher burden of health issues over the lifespan," Somers said.